Multideck rotary switches, also called multi-wafer switches, typically consist of a plurality of contacts arranged in groups. The contacts may be grouped in pairs, in modular form and known as decks or wafers. The decks or wafers may be stacked one upon another. Each contact in a group comprises at least one stationary contact member and one moving contact member. The contact members are electrically connected to terminals accessible to the outside of the switch to which external conductors are connected.
The moving contact members of such a switch are operated by a common rotary control shaft. The shaft typically goes through the center of several decks of a unit formed by stacking a wafer modules. The control shaft may project from one end of the switch. That end normally has fixed thereto a rotary control knob for manual control of the switches. Alternatively, there may be some other control member for switch operation by means of a servomechanism.
The terminals associated with different control members and mounted in a column parallel to the control shaft must be so located as to be readily accessible when the multi-deck rotary switch is connected to external wires leading to the electrical apparatus being served by the switch.
In particular, such switches are typically flush mounted. In such a case, the body of the switch is attached to a supporting panel at its front end, such that the control shaft, which projects from the front end also projects from the panel to a distance sufficient to accommodate the mounting of a rotary control member. Alternatively, they are mounted so as to project from the supporting panel. Such mounting is normally termed a wall mounting with the body of the switch at its back or opposite end from which the shaft projects. Under such an arrangement, the shaft as well as the switch body is mounted on the same side of the supporting panel or wall and the shaft does not penetrate through the wall.
If the terminals of such a switch are arranged so that their axes are roughly perpendicular to the axis of the control shaft it is normally an easy matter to fasten wires to the terminals, as long as the switch is not installed. Thus, choosing between flush mounting or wall mounting of the switch is no problem.
However, experience shows that it is not always easy to make connections for the electrical apparatus to be served once a switch has already been installed. To avoid having such difficulty or indeed the impossibility of making the connections, it is common practice to make the connections in two stages. First, auxiliary leads are connected to the terminals of the switch on a bench, prior to installing the switch. Later, after the switch has been installed, these auxiliary leads are connected to an outside terminal block which also receives the leads from the electrical apparatus to be served by the switch.
This in not an advantageous solution, since it involves double connections and an intendant waste of time and increase risk of making faulty or wrong connections. Besides, this fails to solve the problem of accessing the terminals of an installed switch for servicing purposes.
Accordingly, switches have been designed with terminals arranged obliquely so that their axes are slightly inclined with respect to the axis of the control shaft and with the terminals flaring out from the shaft in a direction away from the mounting end of the switch. This design makes the terminals accessible under all situations, provided access to the back of the switch body is still possible.
On the other hand, it is typically not possible to alternatively flush mount and wall mount a switch with obliquely arranged terminals as described above. In one of these two alternatives, the wall or panel on which the switch is mounted necessarily interferes with the operation of connecting the wires to the terminals, unless the two stage procedure described above is used.
The present invention provides an alternative to the necessity of providing two types of oblique-terminal switch units, one type for wall mounting and another type for flush or panel mounting. The present invention provides a versatile switch design accommodating either mount by the mere permeation of component parts, enabling easy adjustment of the extent of control shaft projection while permitting modification in the number of switching decks making up the switch.